64 dual carburetor issues with 70% to full throttle

[Markus64]

Hi guys,

 

recently I had some issues regarding the engine. When I drive normal everything is fine and the car runs without any issues. Sometimes I give like 70% to full throttle and then it can happen that the engine doesn´t react to this. It makes strange noises and doesn´t accelerate. I have to release the throttle, then the engine reacts normal again. The problem isn´t steady, so sometimes the car reacts like it should and sometimes like discribed.

 

Do you have any ideas, where to start troubleshooting? 

The car has the stock 64 Super Wildcat with the dual carburetor. 

[Jim Cannon]

At that throttle position, you are really opening the secondary throttle plates of both carburetors. Look there.

 

The secondary bores (venturis) have a weighted plate above the throttle plate that swings open in response to air flowing down that half of the carb. Make sure they are free and don't sometimes bind or hang up as they open.

 

There are also fuel passages and jets and such that feed fuel to the secondary venturis; make sure they are all clean and delivering like they are supposed to get a rebuild kit for each carb, take them apart, clean them, reassemble).

 

It may only be one of the two carbs that has a problem.

 

The primary carb has a choke and when the choke is not fully open, the secondary throttle plated are locked out from opening when you step on the throttle quite far.  (It runs like a 2-barrel carb.) So if this problem happens sometimes and not other times, the choke not being fully open may be why.  Look at that too.

 

Good luck. Intermittent problems are no fun to troubleshoot.

 

[telriv]

1st. thing that comes to mind is a clogged fuel filter.

[carbking]

My guesses, in order:

 

(1) choke not functioning normally

(2) partially clogged fuel filter

(3) distributor plate wear

(4) intermittent blockage in fuel tank

 

Jon

[EmTee]

Possible exhaust restriction (e.g., broken muffler baffle)?

[Markus64]

Hi,

 

thanks for your help, the carburetors seem to work fine. The fuel filter is fine too and I think I have an idea what it could be. I have a pertronix 1181 ignitor installed in my ignition distributor. Somebody has installed it before me. The ignitor is directly connected to the coil and gets 6 volt. The manual says that the ignitor requires a 12 volt source away from any voltage reduced circuit. I will change the wiring like it should be and connect it to 12 volt source or change the ignition coil to one which has 12 Volt.

 

Do you have any experiences with the pertronix 1181 and if, how did you install the system in your car? 

Which 12 Volt source would you recommend for this application?

 

In the manual it even says that misfiring or breaking down under load is nearly always associated with low voltage at the unit, which prevents the unit from operating correctly.

I hope this will fix the problem, if not I will continue with your suggestions.

 

 

 

 

[Jim Cannon]

Look at your wiring diagram in the shop manual. Power is fed to the coil through a resistor wire built into the wiring harness. You need to bypass that or run a second new wire from a 12 volt power source that only has power when the key is in the Run position over to the coil. I can tell you how to do that on a '63, but I know that Buick changed the wiring  setup in '64, so I do not know exactly how to bypass the resistor wire on your car.

 

You do not need to change out the coil (unless you really want to).  Just bypass the resistor wire in the power feed to the coil and you are good.

[telriv]

Markus64,

 

    Use a relay that gets powered up by the resister wire. The other goes to a 12 volt source with the key in the run position. The Yellow wire for the electric kick-down is a good & close source. IF it doesn't work out for you you can just dis-connect the wire & relay & go back to the way it was.

No muss, no fuss. Trying to keep it as simple as possible.

Just my thoughts on the subject.

 

Tom T.

[SwedeDownUnderR63]

1 hour ago, Markus64 said:

Hi,

 

thanks for your help, the carburetors seem to work fine. The fuel filter is fine too and I think I have an idea what it could be. I have a pertronix 1181 ignitor installed in my ignition distributor. Somebody has installed it before me. The ignitor is directly connected to the coil and gets 6 volt. The manual says that the ignitor requires a 12 volt source away from any voltage reduced circuit. I will change the wiring like it should be and connect it to 12 volt source or change the ignition coil to one which has 12 Volt.

 

Do you have any experiences with the pertronix 1181 and if, how did you install the system in your car? 

Which 12 Volt source would you recommend for this application?

 

In the manual it even says that misfiring or breaking down under load is nearly always associated with low voltage at the unit, which prevents the unit from operating correctly.

I hope this will fix the problem, if not I will continue with your suggestions.

 

 

 

 

Here is a link to a discussion about installing pertronix including in a 64.

someone even called pertronix and was assured that it could work directly from a lower voltage but only down to 7.5 V.

 

Edited July 17, 2021 by SwedeDownUnderR63 (see edit history)

[Markus64]

Hi Thanks for your information,

 

I connected the pertronix to the yellow wire on the kick down switch, but this isn´t the optimal solution, because during cranking the voltage of the switch drops to 1 Volt, so the car doesn´t start during cranking. It starts in the moment when I turn the key back. Kind of funny behaviour.

 

But as soon as the car is running everything works fine. So i have to look for a different 12 Volt source, which doesn´t drop to 1 Volt during cranking.

Do you have any other ideas?

Edited July 20, 2021 by Markus64 (see edit history)

[RivNut]

FYI, the yellow wire for the kickdown is tied into the wiper circuit/fuse.  

[1965rivgs]

18 hours ago, Markus64 said:

Hi Thanks for your information,

 

I connected the pertronix to the yellow wire on the kick down switch, but this isn´t the optimal solution, because during cranking the voltage of the switch drops to 1 Volt, so the car doesn´t start during cranking. It starts in the moment when I turn the key back. Kind of funny behaviour.

 

But as soon as the car is running everything works fine. So i have to look for a different 12 Volt source, which doesn´t drop to 1 Volt during cranking.

Do you have any other ideas?

  The kickdown switch voltage feed to the ignition coil is for key "on"  position, not in the "crank" mode. While in "crank" mode,  voltage should be supplied to the ignition coil via the contact plate in the starter solenoid. That is why there are two small wires which connect to the starter solenoid.  

. One is the voltage signal from the ignition switch to the starter solenoid intended to engage the starter for the purpose of cranking the engine, and the second wire transfers full system/battery voltage to the ignition coil while the starter solenoid contact is closed (crank mode) to enable easier starting. 

  The original resistant wire from the ignition switch and the wire from the starter solenoid which supplies full system voltage to the coil are joined at a common terminal in the engine wiring harness plug on the firewall side. If you are not getting full  system battery voltage at the coil while cranking, look for a compromise in the wiring between the starter solenoid and the coil.

  Did you leave the original, factory wire connected to the "+" terminal of the coil when you added the additional switched wire lead to the "+" terminal of the coil from the kickdown switch?

  If not, that may be the compromise between the starter solenoid and coil while in the "crank" mode.

Tom Mooney

Edited July 21, 2021 by 1965rivgs (see edit history)

[Markus64]

Hey guys,

 

thanks for your help, I think I solved the issue. I connected a cable from the pertronix directly to the ignition switch at the same connector were the resistance wire for the ignition coil is connected. Now the ignitor gets the full electricty directly from the battery when ignition is on and the ignition coil gets the needed 9 Volts from the resistance wire and all seems fine. No issues at full throttle anymore and the car feels more sporty, gas acceptance is more accurate and it feels like it has more power. 

I needed a while for this because at the same time I replaced my window motor in the front door, and that´s a lot of work when you´ve never done that before.

 

If the issues at full throttle reappear I will continue with your suggestions.